Speaking as a former Nuclear Physicist, some of the greatest scientific minds of the Twentieth Century (especially in Physics) left Germany during that period.
Niels Bohr, James Franck, Albert Einstein, Leo Szilard, Edward Teller, John von Neumann, Hans Bethe, Rudolf Peierls, Joseph Rotblat, Klaus Fuchs, Emilio Segrè, Enrico Fermi
Every one of those names was a man of unbelievable brilliance.
Two examples, not best known by general public:
John von Neumann, (Jonny to his friends) mathematician, concept and design of the explosive lenses on the first atomic bombs (if you don't know what that means you are not alone -elegantly complex mathmatics). Helped develop hydrogen bomb, father of game theory. Von Neumann also helped develop the Electronic Numerical Integrator And Computer (ENIAC), the first electronic general-purpose computer. His ability to instantaneously perform complex operations in his head stunned other mathematicians, and his photographic memory allowed him to recall information without hesitation.
Hans Bethe (see below) could not comprehend von Neumann's incredible intellect: "I have sometimes wondered whether a brain like von Neumann's does not indicate a species superior to that of man."
Hans Bethe, developed microwave radar, selected by Oppenheimer to lead the T (Theoretical) Division of Los Alamos. Taught his whole career at Cornell. He helped to negotiate the 1963 Limited Test Ban Treaty with the Soviet Union. In 1967, Bethe was awarded the Nobel Prize in Physics for his work on how stars produce energy. Having studied Astronomy and Astrophysics, I regard that work as the most important theoretical advance in astronomy since Einstein's General Theory.
These are the kind of minds Hitler drove out of Germany. Pre-Hitler, the whole world acknowledged that Physics in Germany far surpassed all other countries.
"Turn around, you will never see it again!" - Albert Einstein to his wife as they left their house in Germany, December 1932
"I'll be the brains!" - Adolf Hitler to a German journalist who asked him who would be the brains of the country if the Nazis took over, 1931